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Biology terms M to Z.

posted Jul 16, 2016, 2:03 PM by Upali Salpadoru   [ updated Sep 16, 2017, 12:31 PM ]

M..

  • Meiosis 

This is the way cell divides to produce sex cells. The chromosome number gets halved, Ck\lick cell biology.

  • Metabolism

This includes all the physical and chemical changes that occur inside a living being. There are two types. 

Anabolism:- This includes the formation of complex compounds present in the body.

Catabolism:- the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy;

  • Mutation

Copying of proteins is a very reliable process, yet may one in a million a mistake can occur This would cause a mutation.  Most of the errors cause no harm.

The effect caused by the change of the structure in a gene. Only the mutations that may occur in the reproductive cells will be hereditary.

Mutations often lead to evolution. The process may produce an individual more suitable for the environment.

N

  • Nastic movements.

Non directional movements in plants due to stimuli such as temperature.

  • Nephron
nephron.jpg

The function of nephrons is to remove urea, uric acid, and creatinine, and also any excess sodium, chloride, and potassium ions. It can also re absorb water and useful materials such as glucose and maintain the fluid balance.







  • Nephritis
     This is the inflamation of kidneys  due to infection or immunity dis orders.

  • Niche

The place of an organism takes and the role it plays in a particular environment.

  • Nitrogen Cycle

n2.jpg


  • Nucleus
  • nucleus.jpg

  • Fig. Structure of the nucleus.

    This is the most important organelle in a cell.It contains genetic material, chromosomes.






    O

    • Oncogene

    A gene found in the chromosomes of tumor cells which is associated with the conversion of normal cells into cancer cells.

    • Organelle

    This is a structure with specialized functions, in the cytoplasm of an eukaryotic cell.

    • Osmosis

    This occurs when two solutions of un=equal concentration are separated by a semi permeable membrane. Water from the dilute solution diffuses into the more concentrated solution. Usually the solids dissolved cannot pass through the semi permeable membrane.  Plants are able absorb dissolved solids only when they are present in a very dilute form. If a plant root come in contact with a concentrated solution, reverse osmosis can occur.
  • osmosis.jpg
    This is an experiment to demonstrate diffusion. Take two yams carrots or beet root. Make a hole on top as shown Insert a straw and plug it so that water will not leak.
  • Add sugar solution to one and plain water to the other. Fill the first glass with water and the other with a sugar solution. Observe what happens after a few hours.



P

  • Parasites

These are organisms that live or get food from other organisms. There are the ecto parasites that rae found outside the body and endo parasites that live inside.

  • Phenotype

An off spring produced by the combination of hereditary factors as well as environmental conditions.

  • Photosynthesis.
  • Synthesis of primary food by the plants. The reaction is explained by this equation.Water +Carbon dioxide + (Energy from sun light)  =  Glucose + Oxygen.

  • 6CO2 + 6H2O   (Light energy)  = C6H12O6    + 6O2 
  • This reaction can only be performed by chlorophyll the green substance present in plants.
  • Polymerase 

an enzyme that can build long chains of DNA or RNA using the nucleotides

  • Plant

Parts of a dicot  plant.

plant.jpg


  • Plantae
plants.jpg

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         Fig.   Structure of Maize (monocot) and Bean (dicot) seeds.


  • Polymerase chain reaction

A method developed to get copies of DNA very quickly. PCR was discovered in 1983 by K.B.Mullis.  He won the Nobel Prize for Chemistry in 1993.

·         Prebiotics

Prebiotics are carbohydrates in the intestines which cannot be digested. These help the healthy bacteria, probiotics to flourish.

.

R 

  • Recessive allele.
These will become effective only if two copies of the allele are present in an individual. Cystic fibrosis is caused by a recessive allele.
  • Reflex action. An involuntary reaction such as the knee jerk.

  • Respiration

This process conforms to two important functions.

External respiration  - What happens outside the cells, described as breathing or ventilation.

Higher animals use lungs for breathing. Lung respiration

Insects use a system of air ducts.

The fish use gills.

Plants exchange gases through stomata.

Cellular respiration – This is the process by which food is oxidised to obtain

energy. There are two important ways of doing this.

1. Aerobic respiration This is the normal respiratory process using oxygen.

C6H12O6 + 6O2  = 6CO2 +6H2O +( energy, ATP)

Glucose + Oxygen = Carbon dioxide + Water + (Energy)

2. Anaerobic respiration. - This process does not use oxygen.This still takes place among some lower forms of life. Scientists believe that the earliest forms of life would have used this method as there was no oxygen in the atmosphere then. This does not produce as much energy as the other.

Fermantation by yeast is an example of anaerobic respiration.

Reproduction

The ability to make exact copies of oneself may be considered as the specific characteristic of living things. There are many ways of performing this most important task. Let us consider some of them.

A = Asexual Methods

1.    Fission – This is merely dividing a cell and its contents into two or more cells. This process is almost identical to growth. Spirogyra, an algae consists of a row of identical cells. When the cells divide yet they are attached to the filament we call it growth. If they separate and start life as new individuals it amounts to reproduction. In the case of amoeba, a protozoan, binary fission amounts to reproduction.

2.    Budding – This is very common in plants and yeast like specimens but rare among animals. Hydra is a fresh water animal that form new individuals by budding.

3.    Vegetative Propagation-This includes all types of producing new plants from a parent plant. Here are sme examples.

Runners in strawberry.   Leaves in Bryophillum and Begonia.   Suckers in Banana.   Bulbs in garlic   Stem cuttings in Roses.

B- Sexual Method

4.    This method involves the formation of gametes from two individuals and uniting them in a process called fertilization. Gametes contain only half the number of chromosomes which are formed by Reduction Division of cells. The process is also called meiosis. The gametes may be similar or differentiated as male and female. The individual formed by fertilization is called Zygote and would contain a diploid number of chromosomes.

Refer:- Cell division

S 

  • Stem cells

These are the un specialised cells that are capable of dividing and becoming any kind of a specialised cell.

  • Stomata
  • stomata.jpg

These are the opening found on the surface of leaves. The gas exchange for respiration and photosynthesis take place through these openings. Each opening is controlled by two guard cells as it is a disadvantage to lose water, transpiration, through these in times of scarcity.






  • Stretch receptors

 These  are mechanoreceptors, that feel the extension  of various organs and muscles, They  are directly linked to the  brain stem via afferent nerve fibers. Examples include stretch receptors in the arm and leg muscles and tendons.

T

  • Tendril.
  • plants.jpg


  • An appendage of a creeper to climb up a su[pport. Some times leaves or at times the axillary bud gets modified into a tendril that can search for a twijg and coil round it.

  •  Fig. shows an entire bud modified into a tendril.






  • Territory

The area which an animal or a group of a specie defend, to live and protect their young.

  • Tissue

A group of similar cells in a plant or an animal specialised for a purpose. Eg. Blood tissue. Epidermal tissue and vascular tissue in plants.

  • Tropism

The growth of a plant towards or away from a stimulus. Eg Phototropism growing towards light. Geo tropism and Hydrotropism are also examples.

  • Translation

Production of protein according to information in m RNA molecule.

Transpiration

This is the loss of water due to evaporation from plants, mainly from the leaves.

Turgor Pressure

Water enters the plant cells by osmosis. This causes the cell to swell keeping its shape. In the absence of this water cells can collapse.
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